1. Field of the Invention
This invention relates to improvements in oil well pumps and more particularly, but not by way of limitation, to a reciprocal plunger type subsurface pump.
2. Description of the Prior Art
In producing oil wells it is common practice to provide a pump at the bottom of the well bore, or at least down the well bore in the proximity of the producing formation. The pump is normally secured to the lower end of the sucker rod string, which extends longitudinally through the well bore from a reciprocating device at the surface of the ground. The reciprocating device at the surface is usually a horsehead type apparatus and alternately raises and lowers the string of sucker rods in the well bore. Subsurface pumps have long presented many problems in lifting of the well fluid to the surface of the ground. For example, most pumps presently available have an inner barrel or plunger 21/2 feet to 8 feet long which cause friction and drag on the pumper as the plunger reciprocates within the working barrel. As a result it is usually necessary to load the pump by the weight of the rods pushing down on the plunger. If the plunger does not move freely, the plunger may not have a full stroke, thus reducing pumping efficiency. In addition, many of the subsurface pumps have slippage in the operation of the plunger and require several strokes of the pump before a sufficient load is applied to the pump for starting the pumping action. Also, many well fluids contain sand and other foreign particles which greatly hinder the operation of the subsurface pump and frequently damage the working parts thereof. The pumping of heavy viscous fluids also presents a problem to the ususal pump available today.